1. Field of the Invention
The present invention relates generally to surgical instrument holders, and more particularly to a variable force surgical retractor assembly for providing a generally constant retracting force at a desired fixation site despite the possible movement of the fixation site.
2. Description of Related Art
Retractors are commonly used in surgical procedures to provide a surgeon with an unobstructed view of inner portions of a patient's body cavity during a surgical procedure. The retractors are positioned within the cavity of a patient at a fixation site where the retractors contact the object being retracted. The retractors relocate objects obstructing the surgeon's view such as tissue, organs, or other members of the patient. Typically, one or more surgical assistants insert a retractor, or retractors, into an incision surgically created in the patient and hold the retractor(s) in place while the surgeon performs the surgical procedure. The need for surgical assistants to hold the retractor(s) increases the cost of the surgical procedure, and the presence of the surgical assistants provides additional obstacles, such as hands and arms, that the surgeon must avoid during the surgical procedure. Further, The assistants are not able to hold the retractor(s) to maintain a generally constant retracting force on the object being retracted during a lengthy surgical procedure due to fatigue.
Retractor assemblies have been developed to supplant the use of surgical assistants and hold a retractor in place. Typically, the assembly engages an end of the retracting member to hold the retracting member in place relative to the item being retracted. For simplicity, the term “retracting member” is used generally to describe a member that mayor may not include other features, such as a handle, for example, used to apply a retracting force at a fixation site on an object obstructing the surgeon's view during a surgical procedure. Conventional retractor assemblies that accept such retracting members do so by rigidly holding the retracting members in one location. As the fixation site moves during the surgical procedure, such as when tissue being retracted is dissected, or when relaxation of the skin surrounding the tissue being retracted occurs and the skin's elastic properties begin to weaken, for instance, the retracting member being held by a conventional retracting member assembly does not move and loses contact with the fixation site. When this happens, the item that the retracting force was initially applied to often returns to the position it was in before being retracted, and once again obstructs the view of the surgeon performing the surgical procedure.
Retracting members that are capable of being repositioned to maintain the retracting force on an item sufficient to ensure the surgeon has free access to the patient's body cavity exist in the art. An example of such a repositionable apparatus is a retracting member assembly that includes retracting hooks fastened to an end of a ball-and-link chain. The hooks engage the tissue surrounding an incision while the chain is extended to a suitable length. To maintain the length of the chain and thereby maintain the retracting force on the tissue, the balls of the chain communicate with notches formed along the periphery of a platform to restrict further extension of the chain. When the tissue being retracted moves during the surgical procedure, the surgeon, or an assistant, must manually manipulate the length of the chain to allow communication between a ball, located further along the length of the chain closer to the hook, and the notch. This shortens the length of the extended chain and once again provides the retracting force on the tissue. Every time the tissue moves during the surgical procedure and further retraction of the tissue is desired, this process of manually manipulating the length of the chain must be repeated. This requires a momentary cessation of the surgical procedure to manually manipulate the length of the chain, and if performed many times, may prolong a surgical procedure. If repeated manipulation of the chain is not performed, though, the tissue will obstruct the surgeon's view of the interior of the patient's body cavity.
Alternate retracting member assemblies have been developed to permit adjustment of the retracting member to maintain the retracting force applied by the retracting member on objects that move during a surgical procedure. Typically, these assemblies include advanced pressure sensing and control circuitry that is expensive and bulky for an operating room where space for equipment is often limited.
Accordingly, there is a need in the art for a surgical retractor assembly for providing a generally constant retracting force at a fixation site on a patient despite the possible movement of the fixation site during application of the retracting force.